Throughout its history, the motion picture industry has developed new technologies to make motion pictures appear more realistic to audiences than had previously been possible. The advent of sound, color and 70 mm film in the late 1920s added a dimension of realism, when compared to earlier films. The same can be said of developments from the 1950s, such as CinemaScope (wide-screen image achieved through anamorphic compression and expansion), Todd-AO (70 mm film photographed at 30 frames per second with six-channel audio) and Cinerama (three synchronized projectors operating at twenty-six frames per second, projecting films photographed at that frame rate onto a deeply curved screen). While each of these systems increased the sensory impact received by audience members, none of these systems were compatible with each other or with conventional motion picture exhibition systems then in use.
The same is true of the current high-impact systems. IMAX (15-perforation 70 mm film traveling in the horizontal direction) or SHOWSCAN (conventional 5-perforation 70 mm film at 60 fps). The large film frame of IMAX and the high speed of SHOWSCAN limit their use to a few special venues. Conversion of films recorded in these formats cannot be accomplished for use in conventional motion picture theaters without loss of the audience impact gained by use of the special format. IMAX relies on the information packing density of its large frame (70 mm with fifteen performations; three times the normal 70 mm film frame size) to overwhelm the audience and reduce the viewer's awareness of the artifacts that give a "cinematic" look to motion pictures photographed and shown at 24 fps. SHOWSCAN relies on the 60 fps frame rate to reduce the artifacts associated with 24 fps projection. In an attempt to convert 60 fps films to the conventional rate of 24 fps, Trumbull (U.S. Pat. No. 4,889,423 (1989) discloses a method for superimposing the first two images of each group of five shot at 60 fps into a single 24 fps frame, varying the exposure of the two images as superimposed. The next 24 fps frame is likewise made up of the superimposed images of the fourth and fifth frames of the group of images shot at 60 fps. Trumbull's conversion method does not work in practice, since the superimposition of images on each 24 fps frame causes objectionable strobing and blurring of moving objects seen by the viewer. Moreover, the omission of the third frame of each group of five shot at 60 fps interrupts the smooth interpolation of motion available at the higher speed, thereby causing another objectionable artifact.
It is the primary objective of the present invention to allow the mixing of images in a motion picture film that will cause the audience to perceive portions of the image as imparting a strong illusion of reality to the viewer and other portions of the image as having the conventional "cinematic" look associated with the 24 fps frame rate. This allows the audience to perceive certain portions of the images they see as more realistic than other portions of such images, thereby adding a dimensionality to the film as viewed. It is further objective of this invention to provide a means for delivering a high-impact presentation to motion picture audiences and withdrawing the high-impact feature when it is not needed or desired. It is also an objective of the invention to allow easy conversion from the format described into a conventional format for general release and distribution to exhibitors not equipped to show films made in the format described here, without causing objectionable artifacts during the conversion process.
Most silent motion pictures were photographed at 16 fps and shown through a triple-bladed shutter, to give the viewer 48 image impressions per second. With the advent of sound motion pictures, it became necessary to increase the speed of film transport to deliver sufficient sound fidelity. Viewers still saw 48 image impressions per second because frame rate was increased to 24 fps and a double-bladed shutter replaced the earlier triple-bladed shutter. The rate of 24 fps is still the industry standard for conventional exhibition. At this fame rate, there are certain artifacts imparted onto the film upon photography (stropescopic effects and a certain lack of definition, especially moving objects, which appear to blur) that remind the viewers that they are watching a motion picture, rather than live action. The difference between this "cinematic" look of the 24 fps film and the higher impact available at higher frame rates was noted by Trumbull in this original SHOWSCAN, U.S. Pat. No. 4,177,160 (1984) at col. 5, lines 44 to 58:
When such resolution [40 line pairs per mm] is present along with a high illumination level approaching the suggested the [sic] 16.5 foot lambert level, or higher, and with the standard commercial rate of 24 frames per second is used, a bright and clear image is produced. However, in accordance with the present invention, it is found than when these factors of high resolution and light level are used, and in addition, the frame rate at which the image was photographed and later projected is at least 50 frames per second and preferable higher, than an unusual phenomenon occurs. Observers of the resulting motion picture image experience a vivid impression of realism which is greatly enhanced from the level achieved when all the factors are the same except that a slower frame rate such as 24 fps is used.
Trumbull goes on to state that the impact to which he refers is also not available with the IMAX format because of its 24 fps rate (col. 5, line 64 to col. 6, line 10).
Earlier efforts to create that highly realistic effect used the frame rate of 30 fps. Two films, Oklahoma and Around the World in Eighty Days, were commercially released in the 30 fps Todd-AO format. Despite the enhanced realism obtained, the 30 fps frame rate was abandoned because it could not be converted to conventional 24 fps exhibition, thereby preventing wide-scale production of 30 fps films. For general release and exhibition, it was necessary to have a second camera record the same scenes at 24 fps that the first camera recorded simultaneously at 30 fps. More recently, the inventor herein has disclosed a method for transitioning between two different frame rates; specifically 24 and 30 fps (Weisgerber, U.S. Pat. No. 5,096,286 (1992)). This transitioning method used selective underexposure of certain film frames to give the audience the impression of flicker and other artifacts present at the 24 fps frame rate until the film speed had completed acceleration to 30 fps. At that time, a brighter light was switched on to increase the brightness of the image as seen by the audience. The process was reversed for slowdown from 30 to 24 fps.
Noteworthy in the earlier Weisgerber invention is the means to modulate between high-impact (at 30 fps) and "conventional" film experience (at 24 fps). High-impact systems currently in use (such as IMAX and SHOWSCAN) are always "on" and cannot be withdrawn. Such continuous high-impact presentation, even when it is not desired to advance the story line of the picture, can overload the viewer with visual imput; thereby creating an unwanted artifact of its own making.
It is the "cinematic look" of films photographed and shown at 24 fps that is central to the present invention. The differences noted by Trumbull between 24 fps presentation and higher frame rate presentation are precisely the differences in level of the illusion of reality which viewers perceive and that the present invention seeks to modulate. Thus, scenes (or even specific shots) within a single motion picture can have either the conventional cinematic look or the high-impact effect, at the discretion of the director of the picture. More significantly, image parts delivering the high-impact effect can be composited onto the same film frame as components delivering the conventional cinematic look. With the method described here, selected components of a film image can appear hyper-realistic when compared with other image components that the viewers observe simultaneously. As films prepared according to the present invention are shown, audiences will perceive that certain components of the action in the motion picture appear more realistic than other components of the action; thereby approximating the real-life situation where some events have a greater impact of a viewer's perception than others.